2015–2020 GMC Yukon 8L90 Transmission Repair
The 8L90 is paired with the 6.2L V8 in the 2015–2020 Yukon (Denali). 5.3L versions use a different transmission, so we confirm by VIN.
Transmission at a glance
Year-specific notes
- 2015 — 2015 is the 8L90's first model year in GM trucks; early units are the most common subject of shudder-related service updates.
How to confirm your transmission
- RPO code M5U on the glove-box sticker identifies the 8L90.
- 8L90 trucks are 6.2L equipped; most 5.3L trucks of the same years are 6-speed.
- Scan-tool transmission module data confirms the 8-speed unit.
Common 8L90 failure areas in the Yukon
The best-known 8L90 complaint. GM issued service updates involving a fluid change to a revised fluid; we check the truck's history before deeper repair.
Adaptation, valve-body and software level are checked first; hard parts come after that.
Can point to fluid condition, internal leaks or valve-body issues.
Diagnostic considerations
- Confirm software level and whether the fluid service update has been done.
- Review converter slip and clutch fill data on a road test.
- Check fluid condition and level at operating temperature via the check plug.
Repair or rebuild?
Some problems — software, solenoids, a valve body or a converter — can be repaired without removing and fully rebuilding the unit. When clutch packs are burnt or there is metal in the pan, a rebuild (or a replacement unit) is usually the dependable fix. We show you what we found before recommending either.
Closely related vehicles
Some Yukon years were also built with a different transmission depending on engine and trim. Those links are alternative configurations — we confirm your unit by VIN.
Request a quote for your GMC Yukon
Frequently asked questions
Should I rebuild or replace the 8L90 in my Yukon?
It depends on what failed, the mileage and the condition of the case, valve body and converter. We diagnose first, then explain the options before any work begins.
Do you give prices over the phone?
We don't quote a price before diagnosis because repair scope varies widely. Call 602-725-6800 or request a quote and we'll explain the next step.
Where are you located?
MBN Auto Diesel is at 6602 W Myrtle Ave, Glendale, AZ 85301, serving the Phoenix metro.